fix: allocate sizeof(struct data) in prime factoriziation

[SAY-5]

Description of Change

In math/prime_factoriziation.c::int_fact, the local int *range shadows the range typedef on the line above, so malloc(sizeof(range)) reserves only sizeof(int *) bytes (8 on a 64-bit system) instead of sizeof(struct data) (16). Writing pstr->length = count later in the same function overflows the heap allocation.

AddressSanitizer reports the issue on the assignment, matching the report in #1568. After replacing the argument with sizeof(struct data) (one of the two suggested fixes in the issue), ASan runs clean.

References

Closes #1568

Checklist

• Added description of change
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• Added tests and example, test must pass
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Notes: One-line fix to a heap-buffer-overflow in the prime factoriziation example.